1. Field of the Invention
The present invention relates to a method, a system, and a storage controller for controlling shared memories provided in each storage controller to exchange I/O data among the storage controllers that are provided in each of a plurality of disk array devices, which are connected to a network.
2. Description of the Related Art
The burden on computer systems and storages has continuously increased in line with the recent progress in information technologies. Further, there are demands for the computer systems and storages to perform advanced and complicated processes. In view of such a situation, in order to simplify the storages, increase their availability, and meet the increasing requirements for data and applications, importance is now being attached to, for instance, the concept of SANs (Storage Area Networks) and computer clusters. Under these circumstances, storage sharing as well as data sharing is realized. However, the technology for enabling direct data exchange between, for instance, disk array devices composing a SAN has not been established. As a result, various kinds of management information about disk array devices have been managed independently by individual storage controllers for each of the disk array devices.
It is generally true that storage management is facilitated and expedited by interconnecting a plurality of storages via a dedicated network in order to share those storages, as with a SAN. However, host devices, such as application servers, accessing such a storage system or users using those host devices still have to take procedures of designating an address of a specific storage of a disk array device connected to the SAN, informing the address to the Fabric, and acquiring a path to the storage in order to access that storage for use.
More specifically, host devices connected to the SAN recognize the individual disk array devices, as well as the storages that configure each of the disk array devices, as separate storage systems; therefore, it is not possible to access and manage the storages as a single storage system. For such storages, in order to perform various kinds of data exchanging, such coordinating data among the disk array devices or performing remote copying, it is necessary to communicate with a host device via a bus and a channel adapter of the disk array device and acquire a path between the initiator and target. If an enormous amount of data is handled in the above cases, there is a possibility that the bus may be occupied, thereby increasing the processor load excessively and decreasing the system's overall processing efficiency.
Japanese Patent Application Laid-open Publication No. 11-7359 discloses a storage system that comprises a pair of storage controllers but can be seen from an external host computer as a single storage system. In this conventional storage system, the internal buses (or, the “DKC internal networks 137-0, 137-1”) of each of the storage controllers (“Sub DKC0”, “Sub DKC1”) are integrally connected to form an integrated internal network 137. However, since the whole internal buses of the two storage controllers are integrally connected, it is inevitable that the inner configuration of the storage system will become complicated.